Design and control of a three-link serial manipulator for lessons in particle dynamics

Abstract

Design, control, and performance of a ball-throwing robot are examined in this paper. The objective of this project is to provide an interactive ball-throwing robotic arm for illustrating the roles of engineers and computer scientists in the design and usage of such a system to high school or pre-engineering students. Activities in particle dynamics and trajectory calculation will provide basic hands on engineering experience and the opportunity to interact with the robot. In order to effectively provide this activity, the robot must consistently throw the ball from a known point with a desired velocity. This requires a minimum of a two-link manipulator with control strategies sufficient to converge two joint positions and velocities simultaneously. Due to limited micro-controller computational resources, feed-forward torques are calculated offline based on 3 rd order cubic spline trajectories. Feedback compensation for position and velocity error is then examined and compared for ball throwing accuracy and precision to a technique supplementing the previous controller with acceleration error compensation. Experimental results are presented that illustrate the improved accuracy and reduced repeatability the later technique.Gripper design providing consistent hold on the ball and rapid release is also examined.

Throwing motion control based on output zeroing utilizing 2-link underactuated arm

“…Though there are some researches about motion control for throwing an object, most of them about throwing motion control only dealt with accuracy of the target point to which the released ball approaches [6][7] [8]. So, there were few researches about throwing motion control utilizing dexterous features.…”